Draper apron



March 13, 1934. E. K. TWOMBLY 1,951,041

DRAPER APRON Filed April 1952 2 Sheets-Sheet l xii/WWW Patented Mar. 13, 1934 i. TATES DRAPER APRON Earle K. Twombly, Buiialo, N. Y., assignor to Hewitt-Gotta Percha Rubber Corporation,

Buffalo, N. Y.

Application April 7, 1932, Serial No. 603,755

20 Claims.

This invention relates to draper aprons, and particularly to an improved apron and method of making the same.

The draper aprons heretofore in common use, such as for conveying grain in combines, threshers, etc, have been made of untreated tenting duck with side straps of leather or other material riveted or otherwise secured to the apron. Since the leather straps are maintained under tension 10 during use as the driving members of the apron, they soon stretch to such an extent that the web is stretched, and the stretched web soon tears. The duck and leather are also both susceptible to deterioration by weather conditions. Attempts have been made to replace the leather straps by straps made of textile duck which have been impregnated by rubber compounds to make them impervious to weather conditions, and to vulcanize the straps to the web to eliminate riveting. It was discovered that if the straps and the web were stretched and vulcanized under the same conditions as stretched, the straps would stretch further in use and place a considerable part of the strain of operation upon the web which caused early deterioration of the web.

An object of this invention is to provide an improved draper apron which may be made entirely of textile material, such as tenting duck; which may be made iinperivous to weather conditions; which will eliminate the necessity of rivets as the connecting means between the straps and web; with which the operating stresses will be carried largely by the straps; and which will be relatively simple, durable and inexpensive.

Another object of the invention is to provide an improved method of making a draper apron by the use of which the cost of making the aprons will be relatively low; with which a superior and more durable apron will be produced, and which will be relatively simple to practise.

* ther objects and advantages will be apparent from the following description of a draper apron made in accordance with this invention, and representing one embodiment thereof, and of one manner or" carrying out the improved method,

and the novel features will be particularly pointed out hereinafter in connection with the appended claims.

In the accompanying drawings:

Fig. 1 is a perspective of a section of one of the straps of the improved apron, as it appears when only partially completed;

Fig. 2 is a diagrammatic perspective, illustrating an intermediate step in the manufacture of the improved apron;

Fig. 3 is a fragmentary perspective, illustrating another step in the manufacture of the improved apron;

Fig. 4 is a fragmentary perspective of still another intermediate step in the manufacture of the improved apron;

Fig. 5 is a sectional elevation through the vulcanizing press, and showing its relation to the apron;

Fig. 6 is a side elevation of apparatus used following vulcanization in performing another step in the manufacture of the apron, during which the cross bars or cleats are attached to the apron in a uniform and spaced relation; and

Fig. 7 is a plan of a section of the improved apron, when completed.

In accordance with this invention, the straps of the apron which extend along the sides of the web may be formed by folding strips of textile material, such as tenting duck, upon themselves to form a plurality of layers and give the desired thickness. The web is vulcanized or otherwise secured to the straps while the latter are under a stretch which is greater than the stretch of the web, so that the limit of stretch of the straps will be reached before the web reaches its limit of stretch. The web and the straps are impregnated with a rubber compound which makes them, in efiect, almost an integral unit in the finished apron, and the rubber compound protects the fibres of the textile material of the web and straps from destruction by adverse atmospheric influences.

I will now describe one manner of forming the improved apron in accordance with this invention. In forming each strap 10, a strip of textile material, such as tenting duck, is folded upon itself and longitudinally along lines some distance inwardly from each side edge, the folding being over and upon the same face of the strap, with the free edges 10a of the strip in proximity to one another, as shown in Fig. 1. These folded strips are then disposed in parallel spaced relation to one another upon a suitable table 11, with their folded edge portions uppermost, as shown in Fig. 2. The portions of the strips, which are adjacent one end of the table 11, are suitably anchored temporarily to the table, such as by disposing a clamping bar 12 across the table at that end, and resting upon the strips. The ends of the bar 12 are then removably clamped to the table in any suitable manner, such as by adjustable clamping brackets 13 (Fig. 2).

The free ends of the strips are fed between a pair of cooperating belt calendar rolls 14. Suitable means (not shown) is provided for urging the rolls 14 toward one another, so that when the rolls are rotated in any suitable manner in the direction of the arrows in Fig. 2, the strips will be stretched and drawn endwise in the manner that cloths are drawn between the rolls of the ordinary laundry wringer. In fact, the rolls 14 may be urged toward one another and rotated by mechanism similar to that of the usual laundry wringer, and suitable means may be provided for preventing reverse movement of the rolls until release of the strips is desired. This holding, of course, may be obtained by the act of the operator in holding the operating mechanism for the rolls to prevent reverse rotation until it is desired.

The strips 10 are stretched in this manner until the sections between the rolls l4 and the anchored sections of the strips are under the desired stretch, such as a stretch of 10 percent, for example. While the strips are held stretched in this manner, the web 15, which is also formed of textile material, such as tenting duck, is placed upon the table, so as torun in the same direction as the strips, and with the side edges of the web partially overrunning the upper faces of the strips, and preferably with the side edges of the web approximately at those adjacent edges 10a of the related strip which were brought approximately together at the first folding operation, as shown in Fig. 3.

The side edges of the Web are temporarily secured to the stretched strips, such as by means of an interposed layer of unvulcanized rubber compound or cement, which is applied to the abutting faces of the strips and web. The portion of each strip which projects beyond the adjacent edge of the Web is then folded over upon the upper face of the web over as great a length of the web as possible, between the clamping bar 12 and the rolls 14, as shown in Fig. 4, and the folded over-parts are then rolled down so as to temporarily unite the stretched straps to the web which at this time is under no material stretching stress. The straps are then released from .the rolls and the clamping bar 12, and the remaining projecting portions of the strips are at once folded over upon the web and then rolled down.

When the straps are released, they of course contact, and in doing so tend to wrinkle the web and form therein ruifles 16 which run in direc tions transversely of the web, as shown in Fig. '7. The straps and web are next stretched together to an extent somewhat less than the previous stretching, such as 8 percent for the straps, for example. While the apron is thus held in stretched relation, it is clamped between two cooperating vulcanizing platens or units 17 of a standard belt press, as shown in Fig. 5. These platens or units compress thestraps from face to face, but do not touch the web. Each platen or unit 17 is heated, such as by the use of steam chambers 18 in each unit, and this heat vulcanizes the rubber compound with which both the web and straps are impregnated, and firmly and permanently unites the web to the straps, thus making them weather-proof, and practically an integral apron. While no compression is applied to the web by the platens, since the straps hold the platens away from the web, the heat from the platens is sufficient to vulcanize the compound with which this web is impregnated.

After the vulcanizing has been completed, the apron is released from its stretched condition and contracts to some extent, but a great portion of the stretch given the straps during the vulcanizing is maintained, after the release of the apron. The web, after the vulcanizing step, still may retain some of the ruilies 16, but the ruflles of the web are very much smaller than before the second stretching and vulcanization.

It will be observed that approximately 2 percent of further stretch can be given the straps, beyond the stretch which was given them during vulcanization, before the rufiies in the web are eradicated, and consequently when the straps of the vulcanized apron have stretched, say 5 percent in use, the web will be stretched only 3 percent. Since 5 percent represents about all the further removable stretch in the straps, and the possible stretch available in the unprestretched duck is in the neighborhood of 15 percent, it follows that when the apron is in use and subjected to stretching stresses in a lengthwise direction, there will always be less stretching in the web than in the straps, and the limit of stretch in the straps will be reached before the web is very greatly stretched.

Therefore, the stretching stresses on the apron in use will be largely carried by the straps, and there will be very little tendency for the web to crack and tear as has previously been experienced. In other words, because of this stretch differential between the web and the straps, the tearing of the web in use is substantially prevented. The straps and web may be impregnated or coated with the unvulcanized rubber compound at any time prior to vulcanization, but this is most conveniently done before the straps are folded over and rolled down upon the edges of the web. The

unvulcanized rubber compound thus acts as a friction cement and tends to temporarily stick the web to the straps, and hold them in proper and uniform relation to one another in the interval between the two stretching operations.

After the vulcanizing operation, the released apron is placed upon another work table 19 (Fig. 6) which has a plurality of transversely extending, longitudinally spaced slots or grooves 20 in its upper face. Cross bars or cleats 21 are disposed in these slots or grooves 20, usually before the apron is placed upon the table, and these cleats are then secured to the straps of the apron in any suitable manner such as by rivets 22 (Fig. 7) which pass through the cleats and straps.

The cleats extend transversely of the apron, and

will be uniformly spaced in accordance with the spacing of the grooves 20 in the table 19. It may also be desirable to pass rivets 23 through the straps at points intermediate the cleats, as shown in Fig. 7, for contact with the apron guide during the use of the apron.

By folding the strips, of which the straps are formed, in the particular manner illustrated and described, the raw edges of the web and strips will be within the folds of the straps, where they will be protected against the destructive action of weather by the rubber impregnating material which is applied to both the straps and the web and vulcanized thereto. The use of rivets as thev fastening means between the web and the straps is unnecessary, which eliminates the possibility of the rivets tearing or injuring the web in service. Aprons made in accordance with this invention may be manufactured in continuous sections by successive operations upon successive sections thereof, and the cost of manufacture is relatively small.

In the illustrated example of the apron, the warp threads of both straps and web run lengthwise of the apron and parallel to the side edges thereof, but it will be understood that a differential of stretch between the web and the straps may also be obtained by running the threads of one of them, either web or straps, on the bias,

and the web may conveniently be the one whose the degrees of stretch given the straps and the web in the different steps of manufacture of the apron, which have been herein described and illustrated as examples, in order to explain the nature of the invention, may be made by tlkose skilled in the art within the principles and scope I of the invention, as expressed in the appended claims.

claim as follows:

A. draper apron comprising a pair of sub-- stantially parallel straps of textile material connected by a web of textile material, said web and straps being connected to one another while the straps are stretched longitudinally to a greater extent than the web, whereby when the apron is released, the web will be slightly ruffled transversely while the straps are straight.

2. A draper apron comprising a pair of straps of textile material impregnated with a rubber composition, a web of textile material vulcanized at its opposite side edges to said straps, with the straps under greater stretch than the web, whereby the web can be stretched to a greater length before breaking than said straps.

3. A draper apron comprising a pair of straps of textile material, each strap being longitudinally folded and impregnated with a rubber composition and a web of textile material connecting said straps and also impregnated with said composition, with opposite edges of the web received between the folds of the straps and vulcanized thereto while the straps are under greater stretch than said web.

4. A draper apron formed of textile material and comprising a pair of substantially parallel straps of said material connected by a web of textile material, each strap comprising a strip of material folded longitudinally along theoretical lines spaced inwardly from, and parallel to, opposite side edges, with said opposite edges running in proximity to one another after folding, each strap being folded longitudinally a second time at a point between said opposite edges with said edges within the fold, the edges of said web being received between said folds after the second fold, said material being impregnated with a rubber composition, and the straps vulcanized to the web by means of said rubber composition while said straps are under greater stretch than said web.

5. A draper apron formed of textile material and comprising a pair of substantially parallel straps of said material connected by a web of textile material, each strap comprising a strip material folded longitudinally along theoretical lines spaced inwardly from, and parallel to, opposite side edges, with said opposite edges running in proximity to one another after folding, each strap being folded longitudinally a secend. time at a point between said opposite edges with said edges within fold, the edges of said web being received between said folds after the second fold, said material being impregnated with a rubber composition, and the straps vulcanized to the web by means of said rubber composition while said straps are under greater "etch than said web, and cross bars arranged at intervals along said web, and secured to said straps.

6. A draper apron formed of textile material and comprising a pair of substantially parallel straps of said material connected by a web of textile material, each strap comprising a strip of material folded longitudinally along theoretical lines spaced inwardly from, and parallel to, opposite side edges, with said opposite edges running in proximity to one another after folding,

each strap being folded longitudinally a second time at a point between said opposite edges with said edges within the fold, the edges of said web being received between said folds after the second fold, said material being impregnated with a rubber composition, and the straps vulcanized to the web by means of said rubber composition while said straps are under greater stretch than said web, cross bars arranged at intervals along said web, and secured to said straps by rivets passing through the strap and bars, and rivets passing through said strap intermediate said bars.

7. A draper apron comprising a pair of approximately parallel straps of textile material spaced apart, and each folded longitudinally with the open edge of the fold of each strap along the edge nearest the other strap, a web of textile material connecting said straps and extending at its edges between the folds of each strap, said web and straps being impregnated with rubber composition and vulcanized while the web is within the folds of the straps and with the straps under greater stretch than said web.

8. The method of forming a draper apron comprising impregnating a web and straps of textile material with an unvulcanized rubber composition, disposing said straps along opposite edges of said web with the edges of the web in face to face contact with said straps, stretching the web and straps longitudinally to different extents with the straps under the greater stretch, and vulcanizing the straps to the edges of the web while the web and straps are under such stretch to different extents, whereby the maxi- I mum stretch of the straps will be reached before that of the web when the apron is subjected to longitudinal pull.

9. The method of making a draper apron which comprises folding a pair of strips of textile material longitudinally to form straps, disposing a web of textile material between said straps with the side edges of the web disposed between the folds of the straps and with one strap along each edge of the web, impregnating the abutting surfaces of the strap and web with an unvulcanized rubber composition, subjecting the web and straps concurrently to different extents of stress while in assembled relation, and

vulcanizing the rubber composition to unite the L web and straps while the web and straps are under such different degrees of stretch due to tension.

10. A method of forming a draper apron which comprises folding strips of textile material longitudinally to form straps of a plurality of layers, spacing said straps a desired distance apart and approximately parallel to one another, applying a web of textile material to said straps and running parallel therewith so as to connect said,

straps, concurrently stretching said straps and web longitudinally while in assembled relation, with the straps subjected to the greater stretch, and vulcanizing the side edges of the web to the straps with a rubber composition while in that differentially stretched relation to one another.

1-1. A method of forming a draper apron which comprises folding strips of textile material longitudinally to form straps of a plurality of layers, spacing said straps a desired distance apart and approximately parallel to one another, applying a Web of textile material to said straps and running parallel therewith so as to connect said straps, concurrently stretching said straps and web longitudinally while in assembled relation,

with the straps subjected to the greater stretch, vulcanizing the side edges of the web to the straps with a rubber composition while in that differentially stretched relation to one another,

and connecting said straps with cross bars running transversely.

12. The method of making a draper apron which comprises forming a pair of multi-layer straps of textile material treated with an unvulcanized rubber composition, spacing said straps apart and running parallel to one another, placing a web of textile material between said straps, with the side edges of the web abutting face to face with adjacent straps, concomitantly stretching said Web and straps to different extents, with the straps having greater stretch than said web, vulcanizing said web to said straps while in this differentially stretched condition, and then releasing said straps and web, whereby when such an apron is subjected to longitudinal stretch during use, the straps will reach their maximum stretch before the web reaches its maximum stretch.

13. The method of making a draper apron which comprises forming a pair of multi-layer straps of textile material impregnated with unvulcanized rubber composition, spacing said straps apart and running parallel to one another, interposing a web of textile material between said straps and running in the same direction, with the side edges of. the web disposed between layers of said straps, concomitantly stretching said straps and web longitudinally to different extents with the stretch ofthe straps greater than that of the web, and vulcanizing said straps to said web while said straps and web are so stretched to diiferent extents.

14. The method of making a draper apron which comprises spacing a pair of straps of textile material apart and parallel to one another, stretching said straps and holding them stretched, applying a web of textile material to said stretched straps to connect them, with the edges of the web only partially overrunning the straps, impregnating said stretched straps and adjacent edges of the said web with an unvulcanized rubber composition, folding each strap while stretched, longitudinally over the adjacent edge of said web to embrace it, rolling abutting faces of said straps and web into contact with one another, releasing said straps, then stretching said web and straps concomitantly and equally to an extent less than the previous stretch of the straps, and vulcanizing the straps to said web while in that last stretched condition.

position, then subjecting said straps and web simultaneously to stretch of equal amounts and less than the previous stretch of said straps, and vulcanizing the straps and web to one another while in the last stretched condition.

16. The method of making a draper apron which comprises spacing a pair of strips of textile material in a parallel, spaced relation to one another, placing a web between said strips with the side edges of the web partially overrunning the faces of said strips, folding the projecting edges of said strips over upon the side edges of the web so as to embrace the latter, applying an unvulcanized rubber composition to said web and strips, stretching said strips separately from the web, and rolling the folded strips into firm contact with the web while the strips are stretched, then subjecting the web and folded strips to concomitant and equal stretching to an extent less than the previous stretching of the strips, maintaining the stretch, and Vulcanizing the rubber composition in both strips and web while stretched, and then releasing said web and strips.

17. The method of making a draper apron which comprises spacing a pair of straps of textile material parallel to one another, anchoring said straps at one end of the parallel arrangement, applying stretching force to the other and free ends of the straps, disposing a web of tex tile material between said straps and partially overrunning the same, applying an unvulcanized rubber composition to the abutting faces of said straps and web, rolling the side edges of the web into firm contact with said straps, folding the strap between the anchored ends and the stretched ends around the side edges of the web and against the-opposite faces thereof, applying pressure to the folded straps and embraced edges of the web, releasing said straps, completing the folding at the released ends, re-anchoring said straps, restretching said straps and attached web to an extent slightly less than the previous stretch of said straps, applying heat to said straps and embraced web to vulcanize said web and straps to one another, and then releasing said straps and web.

18. The method of making a draper apron which comprises stretching a pair of parallel straps of textile material longitudinally, adhesively connecting, by a rubber composition, the side edges of a web of unstretched textile material to said stretched straps, then subjecting the straps to a lesser degree of stretch, and vulcanizing said straps to said web while under said lesser degree of stretch.

19. The method of making a draper apron which comprises folding each of two strips of textile material in a lengthwise direction to bring opposite side portions over and upon said face of the strap, then further folding each strip longitudinally along a line intermediate its side edges to bring the previously folded side portions upon the inside of the second fold, applying to the abutting faces of the straps a non-vulcanized rubber composition, and inserting a side edge of a web of textile material within the fold of each strap, and vulcanizing the strap to the web'and the layers of the strap to one another.

20. A draper apron comprising a pair of straps of textile duck connected by a web of textile material, said straps and web being initially stretchable to substantially the same extent, said straps being Vulcanized to said web while said straps are stretched and while said web is substantially free from stretch.

EARLE K. TWOMBLY. 

